LEESBURG — A partnership between one of Florida's largest corporations and a Florida retirement community developer plans to make money providing traditional long- term life care to the elderly in an untraditional fashion.

Long the dominion of philanthropic and non-profit groups, retirement communities are attracting the attention of developers who see a lucrative housing market in Florida's growing elderly population.

Stringent state laws have caused many developers to shy away from the traditional life-care setting of providing a vast array of medical and social services for elderly residents. But the partners of ADK Properties are anything but shy about their move into the traditional life-care field.

ADK is preparing to break ground on a $50 million retirement complex on 78 acres near Lake Harris in Leesburg. The project, called Lake Port Square, will be one of the largest commercial ventures in Lake County.

Another $40 million retirement project by ADK is nearing completion in Port Charlotte and the partnership already is scouting other locations in Florida and the Southeast.

Talquin Corp., the real estate development subsidiary of Florida Progress Corp. in St. Petersburg, and The Johnson Simmons Co. in the city of Seminole formed ADK Properties in 1983 to develop life-care communities. Florida Progress owns Florida Power Corp.

''It's a perfect marriage,'' said Kelley Johnson, a partner with The Johnson Simmons Co. ''It fits like a hand in glove.''

Johnson and his father, Richard Johnson, approached Florida Progress officials in 1982 after the completion of Freedom Square, a 393-unit retirement complex that includes a skilled nursing center and an assisted living center in Seminole. The complex features a colonial design that some residents refer to as the ''Disney World in Seminole.''

The success of Freedom Square sold Talquin on the idea of pursuing traditional life-care as a profit-making venture, said Gary Connett, Talquin's director of project development. The complex has a 98 percent occupancy rate. It also didn't hurt that Richard Johnson, former chairman of the board and chief executive officer of Community Banks of Florida, is a close friend of Andrew Hines, chairman of the board of Florida Progress, Connett said.

The combination of The Johnson Simmons Co. with its life-care expertise and Talquin with the backing of Florida Progress, which reported a profit of $161 million on revenue of $1.65 billion in 1985, gives the partnership the financial base to build affordable retirement facilities, Connett said.

Seventy life-care facilities are licensed in Florida, according to the state Department of Insurance. Another 32 facilities have received preliminary approval.

Since 1983, six facilities have failed because developers couldn't sell enough units to cover costs of construction and services for residents, according to the Department of Insurance.

In November 1985, the Department of Insurance placed Lakeview Terrace Christian Retirement Center in Lake County into receivership because the center's owner stopped making payments on a $7.8 million construction loan.

A Winter Park company, Murex Corp., became the new owner under a rehabilitation plan approved by Leon County Circuit Court. The center's former owner, Peter Germeroth, is under investigation for selling $10.4 million worth of unsecured notes to residents and investors, some of whom paid as much as $100,000 for the notes. They will receive partial repayment of their investment from Murex as part of that company's agreement to take over the facility.

Johnson said situations such as that at Lakeview Terrace in which owners and developers ''do not have the residents' interests at heart'' have hurt the life-care industry. To overcome that negative image, Johnson and his partners are involved at almost every level of life care, from attending social functions at South Port Square in Port Square in Port Charlotte to providing congressional testimony on the life-care facilities.

''One of the important things . . . we are in it for the long haul,'' Connett said. ''We're going to operate it the way it should be operated. We're going to be there as long as the residents expect us to be there.''

The primary goal, however, is to make residents feel part of a community rather than a patient at a retirement home, Johnson said. For example, Lake Port Square will have a restaurant, complete with its own chef and menus rather than the cafeteria setting at most retirement complexes.

''We've absolutely shunned institutionalization,'' he said. ''We want our residents to believe they are in luxury retirement apartments. We want to build a resort atmosphere.''